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275 lines
8.1 KiB
C
275 lines
8.1 KiB
C
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/*---------------------------------------------------------------------------
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* Gamedriver: Random Generator 'Mersenne Twister'
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*
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* A C-program for MT19937, with initialization improved 2002/2/10.
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* Coded by Takuji Nishimura and Makoto Matsumoto.
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* This is a faster version by taking Shawn Cokus's optimization,
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* Matthe Bellew's simplification, Isaku Wada's real version.
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*
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* Before using, initialize the state by using init_genrand(seed)
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* or init_by_array(init_key, key_length).
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*
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* Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. The names of its contributors may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Any feedback is very welcome.
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* http://www.math.keio.ac.jp/matumoto/emt.html
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* email: matumoto@math.keio.ac.jp
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*---------------------------------------------------------------------------
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*/
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#include "driver.h"
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#include "random.h"
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/* Period parameters */
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#define N 624
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#define M 397
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#define MATRIX_A 0x9908b0dfUL /* constant vector a */
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#define UMASK 0x80000000UL /* most significant w-r bits */
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#define LMASK 0x7fffffffUL /* least significant r bits */
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#define MIXBITS(u,v) ( ((u) & UMASK) | ((v) & LMASK) )
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#define TWIST(u,v) ((MIXBITS(u,v) >> 1) ^ ((v)&1UL ? MATRIX_A : 0UL))
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static unsigned long state[N]; /* the array for the state vector */
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static int left = 1;
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static int initf = 0;
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static unsigned long *next;
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/* initializes state[N] with a seed */
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void init_genrand(unsigned long s)
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{
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int j;
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state[0]= s & 0xffffffffUL;
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for (j=1; j<N; j++) {
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state[j] = (1812433253UL * (state[j-1] ^ (state[j-1] >> 30)) + j);
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/* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
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/* In the previous versions, MSBs of the seed affect */
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/* only MSBs of the array state[]. */
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/* 2002/01/09 modified by Makoto Matsumoto */
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state[j] &= 0xffffffffUL; /* for >32 bit machines */
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}
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left = 1; initf = 1;
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}
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/* initialize by an array with array-length */
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/* init_key is the array for initializing keys */
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/* key_length is its length */
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/* slight change for C++, 2004/2/26 */
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void init_by_array(unsigned long init_key[], int key_length)
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{
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int i, j, k;
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init_genrand(19650218UL);
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i=1; j=0;
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k = (N>key_length ? N : key_length);
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for (; k; k--) {
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state[i] = (state[i] ^ ((state[i-1] ^ (state[i-1] >> 30)) * 1664525UL))
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+ init_key[j] + j; /* non linear */
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state[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
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i++; j++;
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if (i>=N) { state[0] = state[N-1]; i=1; }
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if (j>=key_length) j=0;
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}
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for (k=N-1; k; k--) {
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state[i] = (state[i] ^ ((state[i-1] ^ (state[i-1] >> 30)) * 1566083941UL))
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- i; /* non linear */
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state[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
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i++;
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if (i>=N) { state[0] = state[N-1]; i=1; }
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}
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state[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */
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left = 1; initf = 1;
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}
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static void next_state(void)
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{
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unsigned long *p=state;
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int j;
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/* if init_genrand() has not been called, */
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/* a default initial seed is used */
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if (initf==0) init_genrand(5489UL);
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left = N;
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next = state;
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for (j=N-M+1; --j; p++)
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*p = p[M] ^ TWIST(p[0], p[1]);
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for (j=M; --j; p++)
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*p = p[M-N] ^ TWIST(p[0], p[1]);
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*p = p[M-N] ^ TWIST(p[0], state[0]);
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}
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/* generates a random number on [0,0xffffffff]-interval */
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unsigned long genrand_int32(void)
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{
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unsigned long y;
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if (--left == 0) next_state();
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y = *next++;
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/* Tempering */
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y ^= (y >> 11);
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y ^= (y << 7) & 0x9d2c5680UL;
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y ^= (y << 15) & 0xefc60000UL;
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y ^= (y >> 18);
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return y;
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}
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#if 0
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/** LDMud doesn't use the following functions - yet. **/
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/* generates a random number on [0,0x7fffffff]-interval */
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long genrand_int31(void)
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{
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unsigned long y;
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if (--left == 0) next_state();
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y = *next++;
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/* Tempering */
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y ^= (y >> 11);
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y ^= (y << 7) & 0x9d2c5680UL;
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y ^= (y << 15) & 0xefc60000UL;
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y ^= (y >> 18);
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return (long)(y>>1);
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}
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/* generates a random number on [0,1]-real-interval */
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double genrand_real1(void)
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{
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unsigned long y;
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if (--left == 0) next_state();
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y = *next++;
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/* Tempering */
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y ^= (y >> 11);
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y ^= (y << 7) & 0x9d2c5680UL;
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y ^= (y << 15) & 0xefc60000UL;
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y ^= (y >> 18);
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return (double)y * (1.0/4294967295.0);
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/* divided by 2^32-1 */
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}
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/* generates a random number on [0,1)-real-interval */
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double genrand_real2(void)
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{
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unsigned long y;
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if (--left == 0) next_state();
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y = *next++;
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/* Tempering */
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y ^= (y >> 11);
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y ^= (y << 7) & 0x9d2c5680UL;
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y ^= (y << 15) & 0xefc60000UL;
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y ^= (y >> 18);
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return (double)y * (1.0/4294967296.0);
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/* divided by 2^32 */
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}
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/* generates a random number on (0,1)-real-interval */
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double genrand_real3(void)
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{
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unsigned long y;
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if (--left == 0) next_state();
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y = *next++;
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/* Tempering */
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y ^= (y >> 11);
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y ^= (y << 7) & 0x9d2c5680UL;
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y ^= (y << 15) & 0xefc60000UL;
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y ^= (y >> 18);
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return ((double)y + 0.5) * (1.0/4294967296.0);
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/* divided by 2^32 */
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}
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/* generates a random number on [0,1) with 53-bit resolution*/
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double genrand_res53(void)
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{
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unsigned long a=genrand_int32()>>5, b=genrand_int32()>>6;
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return(a*67108864.0+b)*(1.0/9007199254740992.0);
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}
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/* These real versions are due to Isaku Wada, 2002/01/09 added */
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#endif
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/*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
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/* Driver interface functions */
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/*-------------------------------------------------------------------------*/
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void
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seed_random (uint32 seed)
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/* Initialize the generator */
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{
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unsigned long init[4];
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init[0] = seed & 0xFFF;
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init[1] = (seed >>= 8) & 0xFFF;
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init[2] = (seed >>= 8) & 0xFFF;
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init[3] = (seed >>= 8) & 0xFFF;
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init_by_array(init, 4);
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} /* seed_random() */
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/*-------------------------------------------------------------------------*/
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uint32
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random_number (uint32 n)
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/* Return a random number in the range 0..n-1.
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*
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* The MT FAQ suggests:
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* If the application is not sensitive to the rounding off error, then please
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* multiply N to [0,1)-real uniform random numbers and take the integer part
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* (this is sufficient for most applications).
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*
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*/
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{
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return genrand_int32() * (1.0/4294967296.0) * n;
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/*
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* Since most compilers compute the constant when it is compiled, so this
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* code runs with the same speed with the standard C codes, and portability
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* and readability are better.
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*/
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} /* random_number() */
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/***************************************************************************/
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